Abstract: The invention provides a method for improving the emotional development of an infant by performing controlled exposure of the infant aged less than six months old to human fear pheromone, preferably with visual fear stimuli, so that the natural synaptic connections in the brain associated with normal fear mechanisms are stimulated and exercised. This can reduce the occurrence of mental illness later in life, in particular reduce the occurrence of schizophrenia. Advantageously the exposure to fear pheromone and visual fear stimuli is terminated and followed by comforting stimuli such as feeding, physical contact, or comforting or happy visual or audible stimuli such as laughter.